The present invention relates to a device and method for interfacing between an integrated circuit and a waveguide and, more particularly, but not exclusively to providing an interface that is efficient at radio and mm-wave frequencies.
A problem arises as to how to create a low loss interface between a millimeter-wave RFIC and a wave-guide.
Current IC production techniques allow a number of types of mechanical structures that can be used to interface IC signals. In order to drive a signal in and out of a wave-guide the mechanical structure needs to comply with specific electromagnetic requirements. In order to drive a millimeter-wave signal between the IC signal interface and the wave-guide's own interface, another mechanical structure is required, the structure having its own electromagnetic requirements in order to drive the electromagnetic signal with minimal loss of signal power.
The difficulty existing today is that the known interfacing techniques still dissipate the signal's power and are relatively complicated and costly to implement. The systems in use today for connecting the integrated circuit to the PCB are wire bonding and tape automatic bonding. Wire bonding uses gold, aluminium or copper wires to connect an IC to a substrate. The bonding is flexible and tolerant of thermal expansion and is also relatively inexpensive. Parasitic effects such as skin effect resistance, radiation loss, mutual coupling between bonding wires, and wire inductances are however present, and difficult to control or model.
Tape automated bonding (TAB) uses patterned metal leads to connect between IC and substrate. An IC is first attached to an inner rim of the patterned leads using gold, aluminium or solder bumps. The attached IC is then mounted on the substrate.
TAB technology can be highly automated, is very precise and allows for gang bonding—meaning that all leads are bonded simultaneously. However the metal leads are of non-uniform width and are closely spaced, leading to electrical characteristics which are difficult to predict or model. TAB technology is also relatively expensive.
U.S. Pat. No. 7,109,122 is an example of the kind of interface according to the current art which still dissipates signal power.
US Patent Application Publication No. 2008/0266196 deals with details of a conventional waveguide feed mechanism.